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West Pacific/2015/09W/Archive/25
Public advisory TROPICAL STORM CHAN-HOM PUBLIC ADVISORY NUMBER 25 WIKI-HURRICANES FORECASTING CENTER 12:00 PM JST MON JUL 06 2015 ...CHAN-HOM REMAINS JUST UNDER TYPHOON STATUS... SUMMARY OF 12:00 PM JST...03:00 UTC...INFORMATION ------------------------------------------------------------------- LOCATION...16.9N 141.1E CENTER POSITION CONFIDENCE: HIGH ABOUT 335 MI...540 KM WNW OF SAIPAN, MARIANA ISLANDS MAXIMUM SUSTAINED WINDS...60 KT...70 MPH...110 KM/H MINIMUM BAROMETRIC PRESSURE...985 MB...29.09 INCHES PRESENT MOVEMENT...WNW AT 10 KT...12 MPH...19 KM/H DISCUSSION AND 48-HOUR OUTLOOK --------------------------------------------- At 12:00 pm JST, the center of Tropical Storm Chan-hom was situated near 16.9N 141.1E, about 335 miles (540 km) west-northwest of Saipan, Mariana Islands. Maximum sustained winds were 60 knots (70 mph, 110 km/h), with higher gusts. The minimum barometric pressure was 985 millibars (hPa; 29.09 inHg), and the cyclone was tracking west-northwest at 10 knots (12 mph, 19 km/h). Environmental conditions are expected to favor steady to rapid intensification over the next 48 hours, and Chan-hom is likely to become a powerful cyclone over the West Pacific. NEXT ADVISORY ------------------- Next complete advisory at 6:00 pm JST. $$ Forecaster TAWX14 Discussion TROPICAL STORM CHAN-HOM PUBLIC DISCUSSION NUMBER 25 WIKI-HURRICANES FORECASTING CENTER 12:00 PM JST MON JUL 06 2015 Chan-hom has changed little in organization since the previous advisory. Although there has been an attempt for the storm to fire deeper convection near the center, a persistent dry air channel continues to negate significant organization. Upper-level outflow continues to expand in all four quadrants, most notably to the west and southwest. Recent satellite intensity estimates were T3.3/51kt from UW-CIMSS ADT, T3.5/55kt from SAB, and T4.0/65kt from JTWC. On that basis, the initial intensity has been held at 60kt, just below typhoon intensity. Environmental conditions are expected to be generally favorable throughout the forecast period. Although the cyclone is dealing with mid-level dry air right now, which is likely to slow development in the short term, sea surface temperatures remain near 30C, ocean heat content continues to be more than adequate, and the upper-level setup is almost as good as it gets for a tropical cyclone. Assuming Chan-hom is able to effectively mix out the dry air and solidify a core, the prospects for rapid intensification remain high. The GFS, ECMWF, and HWRF all continue to suggest that Chan-hom will attain Category 5 intensity over the coming days, and I see little reason to disagree. It is worth noting, however, that the structural changes within the inner core of powerful cyclones are not well forecast at this juncture, and such changes could influence the eventual peak of the cyclone. By the end of the forecast period, the cyclone is expected to move into the China mainland, which should prompt swift weakening. Chan-hom continues to track steadily west-northwest under the influence of a potent mid-level ridge to the cyclone's north. This steering mechanism is expected to dominate the forecast period, and very little change in trajectory is expected. However, it's worth noting that the GFS and HWRF have shifted slightly south over the previous runs, and the updated WHFC track forecast has been nudged in that direction. On the forecast path, Chan-hom is expected to pass closest to the southern Japanese Islands in 96 hours or so before tracking directly into mainland China by day 5. All indications are that Chan-hom will pose an extreme threat to the China mainland by the end of the week. Residents both in the southern Japanese Islands and China should very closely monitor the progress of what is expected to be a large and powerful cyclone. INIT 06/0300Z 16.9N 141.1E 60 KT 70 MPH 12H 06/1200Z 17.5N 139.2E 60 KT 70 MPH 24H 07/0000Z 18.2N 137.9E 75 KT 85 MPH 36H 07/1200Z 19.0N 136.0E 105 KT 120 MPH 48H 08/0000Z 20.1N 134.3E 120 KT 140 MPH 72H 09/0000Z 22.5N 130.1E 140 KT 160 MPH 96H 10/0000Z 25.6N 125.7E 140 KT 160 MPH 120H 11/0000Z 28.2N 120.8E 110 KT 125 MPH...INLAND $$ Forecaster TAWX14